Processes for the preparation of chloroiminophosgene

ABSTRACT

CHLOROIMINOPHOSGENE, USEFUL AS A FUNGISTAT, BLEACHING AGENT AND CHEMICAL INTERMEDIATE, IS PRODUCED BY A PROCEDURE INVOLVING THE REACTION OF CYANOGEN CHLORIDE WITH CHLORINE IN THE PRESENCE OF RADIATION. CHLOROIMINOPHOSGENE IS ALSO PREPARED BY A METHOD INVOLVING ITS CONCENTRATION IN AN ISOLATION FROM CYANOGEN CHLORIDE GAS STREAMS.

United States Patent O No Drawing. Continuation-impart of abandonedapplica- 7 tion Ser. No. 862,519, Sept. 30, 1969. This application May25, 1972, Ser. No. 256,690 V Int. Cl. B01j 1/10 U.S. Cl. 204*1571 R 7Claims 9 ABSTRACT OF THE DISCLOSURE.

Chloroiminophosgene, useful as a fungistat, bleaching agent and chemicalintermediate, is produced by a procedure involving the reaction ofcyanogen chloride with chlorine in the presence of radiation.Chloroiminophosgene is also prepared by a method involving itsconcentration in an isolation from cyanogen chloride .gas streams.

CROSS-REFERENCES TO RELATED APPLICATION This is a continuation-in-partof copending application, Ser. No. 862,519, filed Sept. 30, 1969, nowabandoned.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates toprocesses for the prep aration of chloroiminophosgene orN-chloroisocyanide dichloride of the formula More particularly, thisinvention pertains to a procedure for the production ofchloroiminophosgene by reacting cyanogen chloride and chlorine in thepresence of radiation as well as to a procedure for its production byconcentrating it in and subsequently isolating it from cyano genchloride process gas streams.

The cyanogen chloride/chlorine reaction is illustrated by the followingequation:

This reaction is conducted in the presence of liquid chlorine, an excessof liquid cyanogen chloride with or without an inert completelyhalogenated compound such as carbon tetrachloride, tetrachloroethylene,hexachloroethane and the like. Irradiation is utilized in this reaction,as for example, exposure to sunlight or use of U.V. radiation.

Generally, the reaction is conducted under substantially anhydrousconditions and in the absence of reactive metals. Water and metals suchas iron, sulfate, chloride ions and the like, cause trimerization ofcyanogen chloride to cyanuric chloride.

The reaction temperature can range between about 15 and 50 C. or lowerdepending upon the melting point of the solvent used. A suitabletemperature in the case when cyanogen chloride is used as the solvent isnot in excess of about 20 C. Generally, when lower temperatures areused, the half-life of the resulting iminophosgene is longer.

An alternate mode of synthesis is the following, A gaseous mixture ofcyanogen chloride and chlorine is continuously fed into a glass tubularreactor which is irradiated with ultraviolet light and the temperatureis maintained in the reactor above the temperature at which thechloroiminophosgene liquifies. The chloroiminophosgene is re- 3,801,483Patented Apr. 2, 1974 ice EXAMPLE I Ten grams of liquid cyanogenchloride were saturated with chlorine at 05 C. About 7.0 mole percent C1relative to CNCl was observed by gas chromatographic analysis(Attachment II, B). After transferring the mixture to and sealing in aglass ampoule followed by exposure of the green mixture to sunlight for15-20 hours, the chlorine color disappeared. After cooling the tube to 0C., removing and subjecting a sample to gas chromatography (AttachmentII A, B) there was less than 0.05% (mole) chlorine and 7.7% (mole) ClCNCl correspondingto 14.7% by weight. An active chlorine determinationusing isopropanol solvent and KI/Na S O titration revealed an 8.5% (wt.)active chlorine, corresponding to 15.8% (wgt.) Cl CNCl assuming thestructure Cl CNCl and CNCI, C1 and Cl CNCl to have the same aschromatographic response factors. Results of mass spectral analysisshowing ion fragments at nominal masses 131, 133 and 135 and stronginfrared absorbances at 6.4 and 10.4;1. (and a minor absorbance at 13.4support the proposed structure.

Stability studies indicate that the material has an estimated half-lifeof approximately 40 hours at 40 C. in white light. Based on theretention time on a boiling point gas chromatographic column, thematerial has a boiling point of 83 at 760 mm. It can be purified by areduced pressure distillation procedure.

EXAMPLE II This run was designed to generate suflicient material fordistillation purposes. Approximately 200 g. of liquid cyanogen chloridewas saturated with chlorine at -5 C. to 25 C. and the green liquidtransferred to and sealed in three glass ampoules with a fine oxygenflame. The tubes were allowed to warm to ambient temperature and placedin front of a 1200 watt mercury vapor lamp for thirty minutes, duringwhich time the chlorine color had essentially disappeared.

The ampoules were then frozen and the seal broken. The CNCl mixture wasallowed to melt and then transferred to a distillation flask protectedby a safety shield. After removing cyanogen chloride by refluxing, acrude fraction (94 g.) B.P. 74-82 C./760 mm. was isolated using a 1 ft.x l in. glass Vigreaux column. This material was redistilled thefollowing day using a 1 ft. x 1 in. packed glass column and the materialredistilled under reduced pressure. After refluxing to remove CNCl andC1 a total of 70 g. of Cl CNCl material was collected in the followingfractions:

Fraction I: 62 C./340 mm. (1 g.) Fraction II: 61-62" C./ 340 mm. (15 g.)Fraction III: 62-625 C./340 mm. (55.0 g.).

Residue 1 g. (probably cyanuric chloride). Fraction H was shown by gaschromatography (area percent) to be: 87.8% Cl CNCl, 11.1% CCI, and lessthan 1.0% CNCl/ C1 Fraction III was shown by gas chromatography to be:96.3% ClgCNCl, 3.2% CCL, and less than 0.5% CNCl/ C1 As mentioned abovechloroiminophosgene can also be produced by concentrating it in andisolating it from a gas stream consisting of cyanogen chloride, chlorineand chloroiminophosgene. Chloroiminophosgene is coproduced in smallamounts, e.g. up to 1% in the production oLcyanogemchloridejfOhJ hydrocyni a i drchl ins e.g. in processes for the production of cyanogenchloride as illustrated in US. Pats. Nos. 3,197,273 and 3,567,406.According to this mode of chloroiminophosgene production, the gas streamis absorbed in an inert organic solvent, preferably carbon tetrachloride(since chloroiminophosgene apparently chlorinates slowly to give carbontetrachloride) or hexachloroethane. This solution is fed to a strippingcolumn where the low boiling cyanogen chloride and chlorine are removedand recycled back to the reactor. The chloroiminophosgene/carbontetrachloride solution is fed to a second column where the solvent isremoved continuously overhead and recycled back to the primary absorberor to storage. The higher boiling chloroiminophosgene (B.P. 83 C.) isremoved from the bottom ofthe column (if a higher boiling solvent e.g.hexachloroethane is employed the product is removed overhead). ,Reducedpressure in all distillations may be employed to minimizechloroiminophosgene decomposition to carbon tetrachloride or cyanuricchloride.

"Chloroiminophosgene is useful as a fungistatic agent, as a bleachingagent for paper or fabrics and as an intermediate for the production oforganic isocyanates which are utilized in turn in resin synthesis.

1. A process for the preparation of chloroiminophosgene which comprisesreacting cyanogen chloride, in excess, with chlorine in the presence ofradiation.

2. A process accordingto claim 1 wherein the reactants are in liquidform;

3. A process according to-claim '2 wherein the reaction is conducted ata temperature ranging between about 15 and 50 C.

4, A process according to claim 2 wherein halogenated hydrocarbonsolvent is used.

' 5. A process according to claim 3 wherein the is carbon tetrachloride.

6. A process according to claim 1 wherein the reaction is conductedunder substantially anhydrous conditions and in the absence of reactivemetals.-

7. A process acdording to claim 1 whereinthe reactants are ingaseousform. V

an inert solvent References Cited UNITED STATES PATENTS 3,718,557 2/1973Rogers 612 9.1. .1.-- 204-1571 R HOWARD S. WILLIAMS, Primary ExaminerUNITED STATES PATENT (TFFICE CERTIFICATE OF CORRECTION Patent No.3,801,483 I Dated April 2, 1974 Inventor(s) WILLIAM S. DURRELL, I AL.

It is certified that error appears in the aboveidentified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 7, after "Ala. 36608", insert assigned to Ciba-GeigyCorporation, Ardsley, New York, a corporation of New York Signed andsealed this 13th day of August 1974.

(SEAL) Attest:

McCOY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 .5. GOVERNMENT PRINTINGOFFICE: l9! O-36-334.

